[snarfy]

You're right, that's most likely the main offender. Apologies. I've been consuming a lot of poorly written REST apis lately and am bitter.

[dsego]

The worst one I worked with recently would return 200 and only a human readable error message (no status). On top of that the message is sometimes phrased differently. Here is an example from memory: "The field email is not valid." and "You provided an invalid username."